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Lime Microsystems launched the $139 “LimeSDR Mini,” a size- and cost-reduced sibling of its Ubuntu Core-enabled LimeSDR board, at Crowd Supply.
Lime Microsystems, a developer of field programmable RF (FPRF) transceivers for wireless broadband systems, has gone to Crowd Supply again, to fund a size- and cost-reduced variant of the LimeSDR board that it launched there last year. Like its larger sibling, the LimeSDR Mini is a “free and open source project” that supports the company’s “entirely open-source” LimeSuite host-side software that supports a range of SDRs.

The Mini’s reduced size and cost resulted from implementing a subset of the original LimeSDR board’s features. Specifically, the Mini has a reduced frequency range, RF bandwidth, and sample rate, half as many receive and transmit channels, and significantly fewer programmable logic gates. The key specs of both boards are tabulated below, and more detailed specs for the Mini are listed farther below.

Comparison of LimeSDR and LimeSDR Mini Key Specs

LimeSDR

LimeSDR Mini

Frequency range

100KHz – 3.8GHz

10MHz – 3.5GHz

RF bandwidth

61.44MHz

30.72MHz

Sample depth

12-bit

Sample rate

61.44MSPS

30.72MSPS

TX channels

2

1

RX channels

2

1

Duplex

Full

Interface

1x USB 3.0

Prog. logic gates

40k

16K

Chipset

LMS7002M

Oscillator precision

+/-1 ppm initial, +/- 4 ppm stable

Transmit power

10 dBm max.(depends on freq.)

Open source

Full

Dimensions

100 x 60mm

69 x 31.4mm

Price

$299

$139

The two LimeSDR siblings are also very similar architecturally, as indicated by their respective block diagrams, below.

Block diagrams of original LimeSDR (left) and LimeSDR Mini
(click images to enlarge)

As in the case of its predecessor, the LimeSDR Mini’s FPGA manages DSP and interfacing tasks, while a USB 3.0-connected host system running Snappy Ubuntu Core provides user interface and various high-level supervisory functions. With Snappy Ubuntu Core’s built-in support for an app marketplace, LimeSDR apps can easily be downloaded, installed, developed, and shared. Additionally, the board’s host driver architecture supports both the SoapySDR and UHD APIs, providing further flexibility of application development.

LimeSDR Mini enclosure prototype and its pair of antennas
(click images to enlarge)

The LimeSDR Mini’s on-board firmware supports advanced features such as timed TX bursts and RX sample timestamps, “as required for use with GSM and other time-sensitive protocols,” says the project. The LimeSDR drivers that run on the host system under Ubuntu are built with a “Lime Suite” library that’s said to handle programming and calibration of the LimeSDR board’s LMS7002M FPRF transceiver, as well as other low-level functions.

Operating system support — Snappy Ubuntu Core (Linux), running on USB-connected host system

Further information

The LimeSDR Mini board’s Crowd Supply campaign is currently 65 percent funded. The board is available starting at $139, with options including a $40 case and a $40 antenna set (both are shown above). Shipments, which are free to the U.S. or $10 elsewhere, are expected to begin by the end of this year. More information may be found in the LimeSDR Mini Crowd Supply page.